Cryptosporidiosis as an opportunistic infection in colorectal cancer patients.

Cryptosporidium spp. is an opportunistic protozoan parasite that primarily affects immunocompromised individuals, including those with colorectal cancer (CRC). This study investigates the prevalence and clinical significance of Cryptosporidium spp. in CRC patients, including both the gastrointestinal and respiratory systems. A total of 108 CRC patients and 102 healthy controls were enrolled, and stool, sputum, and saliva samples were analyzed using both microscopy and qPCR methods. Cryptosporidium spp. were detected in 13% of CRC patients' stool samples, compared to 2% in the control group, demonstrating a statistically significant difference ( P  = 0.0013). In contrast, there was no significant difference in Cryptosporidium spp. positivity between CRC patients and controls in sputum or saliva samples. Strikingly, one CRC patient had Cryptosporidium spp. in both sputum and saliva samples in addition to stool, suggesting potential secondary pulmonary involvement. The findings highlight the importance of screening for Cryptosporidium spp. in CRC patients, particularly those with respiratory symptoms, advanced-stage disease, or left-sided tumors, to ensure timely diagnosis and management of this opportunistic infection. Further research is needed to clarify the pathogen's role in colorectal carcinogenesis and the implications for patient outcomes.